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Aerospace and Electronic Systems, IEEE Transactions on

Issue 3 • Date July 1998

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Displaying Results 1 - 25 of 46
  • Comments on "Uncertainty ellipses and their applications to interval estimation of emitter position"

    Publication Year: 1998 , Page(s): 979 - 980
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    The author comments on the work of L.R. Paradowski (ibid. vol. 33, p. 1, 1997) and points out some incorrect projections. View full abstract»

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  • Comments on "Passive target tracking using maximum likelihood estimation"

    Publication Year: 1998 , Page(s): 980 - 981
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (226 KB)  

    The author comments on the work of X.-J. Tao et al. (ibid. vol. 32, pp. 1348-54, 1996 and points out that some of the concepts introduced are debatable. This is backed up with some practical examples. View full abstract»

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  • Comments on "Optimal guidance of proportional navigation"

    Publication Year: 1998 , Page(s): 981 - 982
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (224 KB)  

    The author comments on the work of P.-J. Yuan (ibid. vol. 33, pp. 1007-1011, 1997) in which involved with the target motion parameters seem to have been ignored. In practice, the contact is obtained when the target tracking is on and target motion parameters (range, course, bearing, speed, and acceleration of the target) are found out. Various sophisticated versions of Kalman filter generate estimates with minimum variance. As long as the measurements are corrupted with noise, the estimates contain errors and these are described by covariance matrix of the estimated target state vector. View full abstract»

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  • Comments on "A jerk model for tracking highly maneuvering targets" [with reply]

    Publication Year: 1998 , Page(s): 982 - 983
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (207 KB)  

    The author comments on the work of K. Mehrotra & P.R. Mahapatra (ibid. vol. 33, pp. 1094-1105, 1997) who presented the derivation of covariance matrix of initial estimation of target state vector and the plant noise in detail. In their work the simulation and simulated results seem to be erroneous. Mehrotra replies to these comments. View full abstract»

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  • Author's reply

    Publication Year: 1998 , Page(s): 983
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (98 KB)  

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  • Comments on "Estimation of singularities for intercept point forecasting

    Publication Year: 1998 , Page(s): 1013
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (91 KB)  

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  • Comments on "Estimation of singularities for intercept point forecasting"

    Publication Year: 1998
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    The author comments on an error in the work of A. Satish & R.I. Kashyap (ibid. vol. 32, pp. 1301-1310, 1996) who presented an algorithm for forecasting intercept point in passive target tracking. View full abstract»

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  • Comments on "Canonical transform for tracking with kinematic models" and reply

    Publication Year: 1998 , Page(s): 1014 - 1016
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (232 KB)  

    The author comments on the work of X. Rong Li (ibid. vol. 33, pp. 1212-24, 1997) in which it is mentioned that since the kinematic models are completely observable and controllable, the Kalman filter is stable and will converge to its steady state with a constant filter gain. Alternatively, a simpler implementation is to use directly a Kalman filter with the steady-state gain from the very beginning. It is contended that these statements are debatable. Rong Li replies to the comments. View full abstract»

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  • Author's reply

    Publication Year: 1998 , Page(s): 1015 - 1016
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (246 KB)  

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  • Comments on "Properties and performance of extended target motion analysis" [with reply]

    Publication Year: 1998 , Page(s): 1027 - 1032
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    The author comments on the work of J.P. Le Cadre & O. Tremois (ibid. vol. 32, pp. 66-82, 1996) in which they presented a simple initialization procedure useful for target motion analysis in highly nonlinear systems. However, for the implementation of K, the rate of spatial frequency, it is suggested that the assumptions made are not realistic. Le Cadre & Tremois reply to these comments. View full abstract»

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  • Author's reply

    Publication Year: 1998 , Page(s): 1028 - 1032
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (386 KB)  

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  • Autonomous fault detection and removal using GPS carrier phase

    Publication Year: 1998 , Page(s): 897 - 906
    Cited by:  Papers (4)  |  Patents (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (980 KB)  

    This paper is focused on the use of carrier phase measurements and parity space methodology to investigate the limits of high-integrity and high-continuity satellite-based navigation performance. In this regard, a new algorithm for receiver autonomous fault detection and removal is developed with the specific goal of attaining the high levels of integrity and continuity required for aircraft precision approach and landing applications. Fault detection and removal algorithm performance is demonstrated through analysis and simulation, and the results of tests using deliberately induced failures in raw night data are presented View full abstract»

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  • 2-D wavelet image transforms extended to 3-D with applications

    Publication Year: 1998 , Page(s): 963 - 967
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (460 KB)  

    Mallet and Zhong [1992] have derived some elegant results on 1-D and 2-D wavelet transforms. The objective here is to extend the 2-D results of Mallet and Zhong to 3-D. Illustrated here is how these results can be applied to the feature analysis of 2-D images with time t as the third dimension. An algorithm for extending 2-D to 3-D wavelets is presented View full abstract»

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  • Optimal scheduling of track updates in phased array radars

    Publication Year: 1998 , Page(s): 1016 - 1022
    Cited by:  Papers (11)  |  Patents (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (576 KB)  

    The optimal scheduling of track updates in phased-array radars is considered to minimize the radar energy resources required for track maintenance. The energy-optimal scheduling problem is formulated into a nonlinear optimal control problem, and a numerical procedure for its solution is presented. The scheduling problem is solved for typical examples to illustrate a pair of optimal sequences of track update intervals and signal-to-noise ratios (SNRs) View full abstract»

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  • Binary integration for Swerling target fluctuations

    Publication Year: 1998 , Page(s): 1043 - 1053
    Cited by:  Papers (8)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (528 KB)  

    Binary Integration is a suboptimal approach offering most of the benefits of integration with a simpler and less expensive receiver implementation than optimum coherent integration. We develop accurate, reliable, and efficient methods for binary integration computations for both the constant and Swerling target models. Binary integration introduces a new parameter M, the required number of threshold crossings to declare a detection. With these programs, we can readily do all the calculations necessary to determine the optimum values for M. We find that the assumed loss of 1.5 dB signal-to-noise ratio (SNR) per pulse for binary integration holds for small and large N, not only for the constant targets, but also for the Swerling target fluctuations View full abstract»

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  • Target prescreening based on a quadratic gamma discriminator

    Publication Year: 1998 , Page(s): 706 - 715
    Cited by:  Papers (8)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1016 KB)  

    This work presents the development, analysis and validation of a new target discrimination module for synthetic aperture radar (SAR) imagery based on an extension of gamma functions to 2-D. Using the two parameter constant false-alarm rate (CFAR) stencil as a prototype, a new stencil based on 2-D gamma functions is used to estimate the intensity of the pixel under test and its surroundings. A quadratic discriminant function is created from these estimates, which is optimally adapted with least squares in a training set of representative clutter and target chips. This discriminator is called the quadratic gamma discriminator (QGD). The combination of the CFAR and the QGD was tested in realistic SAR environments and the results show a large improvement of the false alarm rate with respect to the two-parameter CFAR, both with high resolution (1 ft) fully polarimetric SAR and with one polarization, 1 m SAR data View full abstract»

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  • Quick position determination using 1 or 2 LEO satellites

    Publication Year: 1998 , Page(s): 736 - 754
    Cited by:  Papers (4)  |  Patents (8)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1456 KB)  

    We describe an approach for a medium accuracy position determination of a user terminal (UT) on the Earth surface, using one or two low Earth orbit (LEO) satellites. The positioning approach is intended to meet the requirements of a worldwide personal communications system using LEO satellites. The basic two requirements are: (1) immediate positioning, and (2) horizontal position accuracy of the order of 10 km. Those requirements stem from the need of the system to know the user's approximate location before it connects his call. The approach makes use of the two-way communication with the UT, which can receive, transmit, and make its own measurements. Delay and Doppler measurements are used in order to enable instantaneous positioning with one satellite, and in order to achieve unambiguous positioning with two satellites. A simplified Globalstar satellite constellation and the expected Globalstar delay and frequency measurement accuracy are used to demonstrate the concept and to evaluate its performances View full abstract»

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  • Adaptive A/D converter for improved DS/SS jam resistance

    Publication Year: 1998 , Page(s): 810 - 816
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (660 KB)  

    The use of polar nonlinear processing to reject a constant carrier envelope (and possibly wideband) jammer of a DS/SS spread spectrum link is explored, with the additional objective of ensuring constant false alarm rate (CFAR) in the reception of the associated DS/SS synchronization preamble. It is shown that the constant carrier envelope jammer can be rejected very effectively, with CFAR, whether it is transmitted continuously or pulsed at some maximally damaging duty cycle View full abstract»

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  • IMM tracking of maneuvering targets in the presence of glint

    Publication Year: 1998 , Page(s): 996 - 1003
    Cited by:  Papers (13)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (620 KB)  

    A problem of handling multiple types of discrete uncertainties (modes) in a dynamic system is addressed. The dynamic model for a target that exhibits maneuvers (one type of discrete uncertainty) and radar measurements that are perturbed by glint noise (another type of discrete uncertainty) is an example of such hybrid system with two independent mode sets. It is shown how an interacting multiple model (IMM) estimator can be efficiently designed for such systems. Doing the mixing step of the IMM in a number of layered stages, yields some computational savings when the mode sets are independent. Computer simulations are provided for two examples of maneuvering targets in the presence of glint. The results show that the IMM estimator with layered sets of models for glint and maneuver yields better performance (in terms of position and velocity root mean square error) compared with an IMM which handles maneuvers via multiple models and glint via nonlinear “score function” based filters View full abstract»

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  • A new fourth-order processing algorithm for spaceborne SAR

    Publication Year: 1998 , Page(s): 824 - 835
    Cited by:  Papers (35)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1184 KB)  

    A new fourth-order signal aperture radar (SAR) processing algorithm has been developed for a general satellite-Earth relative motion. The two-dimensional exact transfer function (ETF) is calculated and range-variant phase corrections have been calculated in order to process many azimuth lines per block. The ETF together with the phase corrections has been called the fourth-order EETF (extended ETF). It is also shown that a fourth-order EETF is necessary to process high quality images from spaceborne SAR with long integration times with spatial resolution around 1 m. The algorithm is fast and is anticipated to have good phase preservation properties View full abstract»

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  • Optimal time-varying load sharing for divisible loads

    Publication Year: 1998 , Page(s): 907 - 923
    Cited by:  Papers (9)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1196 KB)  

    A load sharing problem involving the optimal load allocation of divisible loads in a distributed computing system consisting of N processors interconnected through a bus-oriented network is investigated. For a divisible lend, the workload is infinitely divisible so that each fraction of the workload can be distributed and independently computed on each processor. For the first time in divisible load theory, an analysis is provided in the case when the processor speed and the channel speed are time varying due to background jobs submitted to the distributed system with nonnegligible communication delays. A numerical method to calculate the average of the time-varying processor speed and the channel speed and an algorithm to find the optimal allocation of the workload to minimize the total processing finish time are proposed via a deterministic analysis. A stochastic analysis which makes use of Markovian queueing theory is introduced for the case when arrival and departure times of the background jobs are not known View full abstract»

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  • Unbiased converted measurements for tracking

    Publication Year: 1998 , Page(s): 1023 - 1027
    Cited by:  Papers (87)  |  Patents (10)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (352 KB)  

    The exact compensation for the bias in the classical polar-to-Cartesian conversion is shown to be multiplicative and to depend on the statistics of the cosine of the angle measurement errors. An unbiased conversion is presented. A comparison between this unbiased conversion and the previously presented debiased conversion is made. The unbiased spherical-to-Cartesian conversion is also presented and evaluated View full abstract»

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  • Optimal observer maneuver for bearings-only tracking

    Publication Year: 1998 , Page(s): 777 - 788
    Cited by:  Papers (49)  |  Patents (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (952 KB)  

    In bearings-only tracking, observer maneuver is critical to ensure observability and to obtain an accurate target localization. Here, optimal control theory is applied to the determination of the course of a constant speed observer that minimizes an accuracy criterion deduced from the Fisher information matrix (FIM). Necessary conditions for optimal maneuver (Euler equations) are established and resolved, partly by analytical means and partly by an iterative numerical procedure. Examples of optimal observer maneuvers are presented and discussed View full abstract»

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  • Target orientation estimation using Fourier energy spectrum

    Publication Year: 1998 , Page(s): 1009 - 1012
    Cited by:  Papers (4)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (536 KB)  

    Orientation estimation is an essential step in autonomous navigation, automatic target recognition, part handling, and many other machine vision applications. A procedure is presented to estimate the orientation of the target using spectral energy distribution in the Fourier domain. The performance of this technique is determined by conducting simulation experiments on a set of infrared images containing military targets View full abstract»

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  • CFAR detection and estimation for STAP radar

    Publication Year: 1998 , Page(s): 722 - 735
    Cited by:  Papers (13)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (996 KB)  

    The algorithm presented here provides both a constant false-alarm rate (CFAR) detection and a maximum likelihood (ML) Doppler-bearing estimator of a target in a background of unknown Gaussian noise. A target is detected, and its parameters estimated within each range gate by evaluating a statistical test for each Doppler-angle cell and by selecting the cell with maximum output and finally comparing it with a threshold. Its CFAR performance is analyzed by the use of the sample matrix inversion (SMI) method and is evaluated in the cases of a fully adaptive space-time adaptive processing (STAP) and two partially adaptive STAPs. The performances of these criteria show that the probability of detection is a function only of the sample size K used to estimate the covariance matrix and a generalized signal-to-noise ratio. The choice of the number K is a tradeoff between performance and computational complexity. The performance curves demonstrate that the finer the resolution is, the poorer the detection capability. That means that one can trade off the accuracy of ML estimation with the performance of the CFAR detection criterion View full abstract»

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IEEE Transactions on Aerospace and Electronic Systems focuses on the equipment, procedures, and techniques applicable to the organization, installation, and operation of functional systems designed to meet the high performance requirements of earth and space systems.

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Editor-in-Chief
Lance Kaplan
Army Research Laboratory